Retractile device



Aug. 4, .1931. F. A. voos RETRACTILE DEVICE Filed May 21, 1930 'lNl/ENTO/P F. A. V005 ATTORNEY I Patented Aug. 4, 1931 F EDsB cK-nfvocs, or; ASSIGNOR 'ro BELL TELEIHONE ieiioaemoa ii K,

i is ie le ay 21,

'Thisinvention'relates to retractile spring assemblies andparticularly to those used for the release of switches employed in telephone and othersystems. I

5 The objects. of the invention. are to'reduce the number of failures in operation, torender thesedevices nore positive and reliable, to facilitate adjustment, to reduce the cost of manufacture, and to'otli'erwise effect im: provements therein. V a

' has been the ciistomin the past to use coil springs, such as those" employed in clocks, for therestoration of the shafts of g I automatic switches. flhese springs have not been found entirely satisfactory diietothe friction offered by contact between adjacent 'convolutions, since they are liable to lock in their tensioned condition preventing restoration of the shaft, since they are subject to breaking, and o n account of the fact that. they are costly to manufacture and inaintain in adjustment. J The present invention is an improvement over the devices-of the priorfart in that itfenablle's the use of a helicaltype' spring whiclris better suited for the release, of switch shafts and canbe attached to present standard switches without necessitating any. changes. "These r'esitlts' are secured by means of a spring assembly which. includes an entensiontube that fits on over the end of the standard switch shaft and is firmly secured thereto by meansfof a setiscrewl- Theretrac'tile spring, which may take the shape of an inverted cone, is secured at one end toa .collar on the,extensiongtiibe- The free end oftlie'sprin'g is secured'tofan adjusting cap which carries a small bushing tha't fits into the upper end ofthe extension. tube and provides a bearing for'rotation of the cap with respect to the tube. The adjustingcap has slots .around its periphery into which a locking spring inember fits to holdfthe' cap against rotation when. the spring is tensioned. The locking spring element is secured to the hi b member efthe stopv bracket which engages the stationa'ry post on the switch frame. To adj'u'st the tension ,ofv'the' spring," i't'is .onfly necessary to'disengagethe locking'spring from the RETRACTILE DEVICE INGORPGRATEI), Oi" YORK, 1?..Y.,. A CORPORATION OF NEW 1930. Serial No. 454,477.

slot in the adjusting cap, rotate the cap i'etra ctile spring and its associated elements may readily be attached to the standard switch shaft in replacei'nent of the spring devices now used without disturbing the 7 stop finger that limits the restoring movement ofthe switch.

Although it has been proposed heretofore to use helical-springs for the restoration of switches, applicants invention is an improvement over these prior devices in that it materially facilitates replacement and makes it possible to secure a correct adjust} inent with the least amount of difficulty.

The invention is illustrated in the accompanying drawings in which Fig. 1 shows a portion of a two-movement step-by-step selector switch including the retractile device for restoring the brush shaft to its I normal position. Fig. 2 is an enlarged view of the retractile assembly showing the various elements partly disassemhledf Fig. 3 is a detail of theassemblyshowing the manner in which the stop finger is attached to the shaft. Fig. at is an assembly view partly in cross section showing an alternative form of retractile spring. Inasmuch as the construction and operation of selectorswitches of the type to which this invention is applicable are well-known to those skilled in the art, it is not considered necessary to show the full details of such aswitch. Reference,however, may be made to the patent to Keith et al. No. 815,

' 176, granted .March 13, 1906.

Referring first to Fig. 1 of the drawings, the brush shaft 1 of. a switch of this kind carries a plurality of brushes 42, 4:3 and {it which cooperate with rows of contacts in a tennina-lbank, not shown. A set of verti cal operating magnets 28 inou itedlon the swi-tchfraine operate an armature 29,}which in turn act ates thestepning pawl 30. Pawl 30 engages the vertical ratchet 34 to step the brush shaft vertically in a step-by-step 'manner. The. shaft 1 is held in its vertical position by the holding dog 38. After the 7 switch has been positioned in its vertical direction, the rotary magnets 31 are energized to operate the armature 32, which in turn actuates the rotary stepping pawl 33. The pawl 33 engages the rotary ratchet 35 to rotate the shaft 1, which advances the associated brushes into engagement with the sets of terminals inthe terminal bank; The

shaftil is heldv in its rotary position by the During the vertical movement of the brush shaft, the retractile spring assembly, connected] to the top of the shaft, moves bodily therewitlr' During the rotary movement of the shaft 1, the retractile spring is tensioned so as to restore the shaft in its rotary direction whenthe shaft is released.

' The release of the shaft is effected by ener- -izin the'releaseIma 'net 36 to disen a e the holdingdogs 38"and '39. .The shaft re-' leases first in its rotary direction and then in its vertical direction. To accomplish this, the shaft is prevented from restoring in its vertical direction until it has completely restored in its rotary direction by means of a further holding dog, not illustrated in the drawing. It-will be seen from the drawing that a vertical slot 4:7 is cut in the teeth of the ratchet 3 1. A stationarydog'lies fits feasily on over the brush shaft 1. The

tube 2 has an integral hub portion 3 tapped the holding within this slot when the shaft is in its normal rotary position. As soon, however, as a rotary step is takemthe dog passes under the corresponding rotary tooth in the ratchet 34:; This holds the shaft'against release vertically untilit has restored toflits normal rotary position," regardless of the fact that dog 38 may'have been withdrawn. v

The spring assembly comprises an extension tube 2 (shown in Figs. 2 and 1) which to receive a set screw 42 The spring assenr.

bly also includes a locking spring 6, a bush- .ing 5, and a stop bracket 8. Thelower porelements after being assembled are securely tion 12 of the bushing 5 is ofreduced di-v ameter toreceive the locking spring 6 and thestop bracket 8 when assembled. These held together'as, a unit byturning over a portion of the'bushing, or in any other suitable manner. When these elements have been assembled, a projecting portion 7 fof the spring 6 enters the notch 9 onthe bracket 8. This is asafeguard against any relative rotary movement between the assem bled parts;

The brush shaft 1 is provided with a slot 16, into which the stop finger 15 snugly fits. With the stop finger 15 properly adjusted in the slot 16 and with the clevis 1 1 in place .as illustrated, a set screw 17 is tightened holding dog 39 engaging the rotary ratchet o0.

to firmly secure the clevis and stop finger to the shaft 1. After the stop finger and clevis have been fastened to the shaft, the unit including the stop bracket 8., bushing 5 and locking spring 6 is passed on over the shaft until it rests upon theupper surface of the clevis 14. 'With the elements thus assembled,

the extension tube 2 is passed over the shaft until the lower reduced portion thereof enters the bushing 5 and the hub 3 comes to rest in contact with the upper surface of said bushing. The set screw 4 ishdwtightened to securely attach the extension 2 to the shaft 1. In tightening the set screw 4:,suf-

ficien't clearance is'allowed to permit the shaft 1 and. tube2 to rotate with respect to the bushing 5. I Q 7 j The assembly also includes a retractile spring comprising a bushing or bearing piece 18, an adjusting cap 19, and a helical spring 25. The cap l9'ma'y be formed in any suitable manner from sheet metal and is provided with a depressed central portion having a concentric aperture therein which receives the upper reduced portion of the bushing 18-. The upper end of the bushing is turned over, as best seen in Fig.

1, to securelyfhold the bushing and cap together as a' unit. The lower portion of the bushing 18 enters the upper end of theex-' tension tube 2 to permit free rotation of the extension tube with respect to the cap 19 and also to serve as a'bearing area to hold the parts in proper relative position during actuation ofthe switch shaft. The retractile spring25 at its lower end entersthe aperture 13 in the hub '3 to secure the lower end of the spring'to the shaft 1. The upper end of the spring hasa loop" 27 which engages an aperture 2% in the side wall of the depressed portion, of the adjusting cap 19. The cap 19 is provided with-a plurality of notches 20, 21, 22 and 23 equally spaced about the periphery thereof. 1 The purpose of these notches is to receive the upper or free end of the locking spring 6 to'hold'the adjusting cap 19 against rotation due to the tension of the spring 25.

With all partsfully'assembled, as illustrated in Fig. 1, the stop bracket 8 is held against rotation by means of the normal post 41,.which is secured tothe frame 40 of the switch and which freely enters an aperture 10 in the stop" bracket. 'Dur ing'vertic'al movement of the switch, the

stop bracket slides up and down the post 41, but is'not permitted to participate in the rotary motion of the shaft. In this manner the locking spring 6 is held against rotation since it is secured to the stop bracket, andthus the adjusting cap 19 is preventedfrom rotating due to the engagement ofthe lockingspring 67in one of the notches 20, 21, 22 or 23. The upper'end 4&5

of the spring 6 is ,shaped so as to lock the extension tached to said shaft, an ad usting cap atadjusting'cap 19 in a vertical direction thus preventing the bushing 18 from Working loose due to the tension 011 the spring 25.

In order to adjust the spring 25 to the proper degree of tension, the locking spring 6 is disengaged from the adjusting cap 19, the cap seized and given the requisite number of turns against the tension of the spring 25, and the locking spring 6 reengaged witl the proper notch in said cap. With the spring 25 under tension the shaft 1 is urged toward its normal position, the limit of which is determined by engagement between the stop finger l5 andthe depending portion 11 on the stop bracket 8; Since the stop finger 15 presses against the bracket 8, the forces of thespring are confined within the assembly so that the stop bracket 8 offers no friction as it slides along the normal post l1 during the vertical movement of the switch. 1

The retractile spring 25 illustrated in Figs. 1 and 2 is conical in shape. In Fig. 4 a modified form of spring 46 is illustrated which is cylindrical in shape.

hat is claimed is:

1. In combination, a rotatable shaft, an

piece having one end securely a tached to'the other end of said extension piece for rotation relative thereto, a spring surrounding said extension piece and having one end secured thereto, the other end of said spring being attached to saie adjusting cap, and'a locking spring element having a detachable engagement with said cap to hold the same against rotation.

2. In combination,'a rotatable shaft, an extension piece, having one end secured to said shaft, a retractile spring surrounding said extension piece and having one end secured thereto, an adjusting member attached to the other end of said extension piece and arranged for rotary movement relative thereto, the other end of said rotractile spring being secured to said adjusting memher, and alocking spring element arranged to en a e an one of'a series of notches in said adjusting member to hold said adjusting member against rotation with said shaft.

3. In combination, a rotatable shaft, a hollow extension piece one end of which receives the end of said shaft, means for securing the extension piece to said shaft, an adjusting member associated with the other end of said extension piece and arranged for rotary movement relative thereto, a helical spring surrounding the extension piece, one end of said spring secured to said extension piece and the other end attached to said ad usting member, and a locking element for adj ustably engaging and holding said adjusting member against ro tation. f

l In combination, a rotatable switch shaft, an extension tube, one end of which receives said shaft, means for securing said tube to the shaft, an adjusting cap having a bearing piece which enters the other end of said tube to permit rotary movement of said cap with respect to the tube, a helical spring having one end secured to the extension tube and the other end attached to said adjusting cap, a locking spring for detachably engaging said adjusting cap to hold the same from rotating, and means securedto said adjusting spring to prevent the same from participating in the rotary movement of said shaft.

, 5; In combination, a rotatable shaft, a hollow extension piece, one end of which receives. the end of said shaft and is securely attached thereto, an adjusting cap havinga bearing element which enters the free end of said extension piece to permit rotation of the cap with respect to said extension piece, said cap having a series of notches in the periphery thereof, a retractile spring surrounding said extension piece having one end secured thereto and the other end attached to said adjusting cap, and a spring element having one end fixed and the other end arranged to detachably enga e'said notches to hold said. adjusting cap from rotation under the tension of said retractile spring.

6. In combination, a shaft, an extension piece, one end of which receives the shaft and is secured thereto, an adjusting memher, having a bearing and cap .element, which engages-the other end of said extension piece to permit rotary movement of the adjusting member relative to said extension piece, a helical retractile spring for restoring said shaft to its normal position, one end of said spring secured to said extension piece and the other end attached .to said adjusting member, and a locking spring for adjustably engaging said adjusting member to hold the same against move ment. under the tension of said retractile sprin 7. In combination, a rotatable shaft, an extension tube, one end of which receives said shaft and is secured thereto, a stop bracket associated with said shaft and serving to limit the rotary movement thereof, a helical spring surrounding said tube and having one end secured thereto, an adjustable cap attached to the free end of said spring and having a bearing and guide element which loosely fits in the other end of said extension tube, and a locking element having one end secured to said stop bracket and the other end adjustably engaging said adjusting cap to hold the same against rotation under the tension of said helical spring.

8. In combination, a rotatable shaft, a

hollow member, one end of which receives it?) 7 the end of said shaft and is securely at V tached thereto, a stop bracket encircling said V curely attached to said stop bracket and the shaft and serving to limit the rotary movement thereof, a stop finger secured to .the shaft and engaging said stop bracket in the normal position or the shaft, a cylindrical retractile spring surrounding said hollow member and having one end secured thereto, an adjusting member attached to the other end of said spring and attachedto said hollow member for rotary movement relative thereto, and'a locking spring having one end encircling said shaft and 'seother end flexibly engaging said adjusting member to hold the sameagainst. relative V movement with respect to said step bracket;

9.111 combination, a stationary frame, a rotatable shaft supported by'said frame, an extension piece, one end of which is securely attached to the end of said shaft, a spring for restoring said shaft, a cap member engaging the other end of said extension piece in such a manner as to permit free rotation of the extension piece with respect to said cap member, and a locking .springfor detachably engaging said cap member to hold the same firmly in engagement with said extension piece and also to prevent said cap member frompartieipating in the rotary movement of said extension piece. 7

10. In combination, a rotatable shaft, a tube, one end of which receives the end of said shaft and is securely attached thereto, a circular cap having a bearing element which loosely fits in theother end of'said tube topermit rotary movement of the tube with respect to the cap, said cap having a series of notchesin the periphery thereof,

a helical spring surrounding said tube having one end secured thereto and the other end attachedtoisaid cap, and. a locking member for engaging any one of said notches to-hold said cap against displacement with respect to said extension tube and also to hold said cap member from participating in the rotary movement of said extension tube.

In witness whereof, [hereunto subscribe 16th day of May, 1930. c FREDERICK A. VOOS. i

my name this 

